Identity Group

An identity group is a business-meaningful collection of instances of a given aggregate type. It allows us to run commands or queries against a set of these aggregates, either as the set stands now or as it stood at a particular point in time, without having to know the underlying technical implementation that specifies if an instance should be in that group or not.

This is conceptually similar to the SQL WHERE CLAUSE way that queries and updates are applied to subsets of the business data in a relational model.

For example in a banking system there might be identity groups for "Open Accounts", "Accounts In Credit" and so on.

Identity groups can be nested if the business logic dictates - for example every member of the identity group "Accounts In Credit" would be in the identity group "Open Accounts".

Membership of an identity group is evaluated by running a classifier over it.